theorem minle1 (a b: nat): $ min a b <= a $;
    
      
        | Step | Hyp | Ref | Expression | 
|---|
        
          | 1 |  | eqle | min a b = a -> min a b <= a | 
        
          | 2 |  | ifpos | a < b -> if (a < b) a b = a | 
        
          | 3 | 2 | conv min | a < b -> min a b = a | 
        
          | 4 | 1, 3 | syl | a < b -> min a b <= a | 
        
          | 5 |  | ifneg | ~a < b -> if (a < b) a b = b | 
        
          | 6 | 5 | conv min | ~a < b -> min a b = b | 
        
          | 7 | 6 | leeq1d | ~a < b -> (min a b <= a <-> b <= a) | 
        
          | 8 |  | bi2 | (b <= a <-> ~a < b) -> ~a < b -> b <= a | 
        
          | 9 |  | lenlt | b <= a <-> ~a < b | 
        
          | 10 | 8, 9 | ax_mp | ~a < b -> b <= a | 
        
          | 11 | 7, 10 | mpbird | ~a < b -> min a b <= a | 
        
          | 12 | 4, 11 | cases | min a b <= a | 
      
    
    Axiom use
    axs_prop_calc
     (ax_1,
      ax_2,
      ax_3,
      ax_mp,
      itru),
    
axs_pred_calc
     (ax_gen,
      ax_4,
      ax_5,
      ax_6,
      ax_7,
      ax_10,
      ax_11,
      ax_12),
    
axs_set
     (elab,
      ax_8),
    
axs_the
     (theid),
    
axs_peano
     (peano1,
      peano2,
      peano5,
      addeq,
      add0,
      addS)